4.3.2.3 Latent Heat

Spec reference: 4.3.2 (subtopic).

What you need to know

• Latent Heat
• Energy is being put in during melting and boiling. This increases the
• amount of internal energy. The energy is being used to break the bonds,
• so the temperature does not increase. This is shown by the parts of the
• graph that are flat.
• When a substance is condensing or freezing, the energy put in is used
• to form the bonds. This releases energy. The internal energy decreases,
• but the temperature does not go down.

Self-assessment (checklist)

• I can give a definition for specific latent heat.
• I can distinguish between the specific latent heat of
• I can describe what happens to the energy transferred
• I can calculate the energy change involved when
• I can interpret heating and cooling graphs that include
• I can distinguish between specific heat capacity and

Key steps (method)

• Identify what the question is testing and use the correct equation/definition.
• Show substitutions and units clearly.

Common mistakes

• Unit conversions, rearranging errors, or quoting a law without applying it.